Whole blood is routinely separated into its various components, such as red blood cells, platelets, and plasma. In many blood processing systems, whole blood may be drawn from a donor, the particular blood component or constituent removed and collected, and the remaining blood constituents returned to the donor. By thus removing only particular constituents, less time may be needed for the donor's body to return to normal, and donations can be made at more frequent intervals than when whole blood is collected. This may increase the overall supply of blood constituents, such as plasma and platelets, made available for health care.
One method by which whole blood may be separated into its constituents is centrifugation. Whole blood may be passed through a centrifuge after it is withdrawn from, and before it is returned to, the donor. To avoid contamination, the blood may be contained within a sealed, sterile system during the entire centrifugation process. Blood processing systems thus may include a permanent, reusable centrifuge assembly or “hardware” that spins and pumps the blood, and a disposable, sealed and sterile fluid processing or fluid circuit assembly that actually makes contact with the donor's blood. The centrifuge assembly may engage and spin a portion of the fluid processing assembly (often called the centrifuge or separation chamber) during a collection procedure. The blood, however, may make actual contact only with the fluid processing assembly, which may be used only once and then discarded.
It is desirable for blood processing systems to have features that preserve the longevity of hardware and parts as well as optimize the mechanics of the processing procedure.